Biodegradation of photosynthetically produced extracellular organic carbon from intertidal benthic algae

14C-labeled extracellular products of a natural microphytobenthic community and two species of benthic diatoms (Nitzschia hybridaeformis and Amphora coffeaeformis) were fractionated into extracellular dissolved organic carbon (14C-EDOC), organic carbon extracted with EDTA (14C-EDTA-extractable OC) and extracellular polymeric substances (14C-EPS). The biodegradation of this labeled extracellular organic carbon by bacteria in sediments was examined to determine the processes of enzymatic degradation of photosynthetically-produced extracellular organic carbon from microphytobenthos in an intertidal flat ecosystem. In addition, primary production as well as extracellular enzyme activities (beta- and alpha-glucosidase) were measured to evaluate the possible relationship between organic carbon production and microbiological degradation at the Isshiki intertidal flat in Mikawa Bay, Japan. With all three 14C-fractions extracted from a natural microphytobenthic assemblage and two species of benthic diatoms, more than 50% of the added substrates were mineralized within 24 h by the bacterial community in sediments. At that time, the percentage of high-molecular-weight compounds (>5 K MW) to total MW compounds of 14C-EDTA-extractable OC and 14C-EPS fractions decreased within 24 h from 50.9 to 6.6% and 74.5 to 11.1%, respectively. In situ, beta- and alpha-glucosidase activity in sediment was higher than in the seawater column (at a depth of 1 m), though the photosynthetic production of microphytobenthos was equal to that of phytoplankton. Based on our previous studies that microphytobenthos produced much more extracellular products than phytoplankton, it is assumed from these results that carbon flowing into the microbial loop through the mediation of enzymatic degradation of extracellular products in a benthic system exceeds that in the overlying water column.     

Coccolithophorid algae culture in closed photobioreactors

The feasibility of growth, calcium carbonate and lipid production of the coccolithophorid algae (Prymnesiophyceae), Pleurochrysis carterae, Emiliania huxleyi, and Gephyrocapsa oceanica, was investigated in plate, carboy, airlift, and tubular photobioreactors. The plate photobioreactor was the most promising closed cultivation system. All species could be grown in the carboy photobioreactor. However, P. carterae was the only species which grew in an airlift photobioreactor. Despite several attempts to grow these coccolithophorid species in the tubular photobioreactor (Biocoil), including modification of the airlift and sparger design, no net growth could be achieved. The shear produced by turbulence and bubble effects are the most likely reasons for this failure to grow in the Biocoil. The highest total dry weight, lipid and calcium carbonate productivities achieved by P. carterae in the plate photobioreactors were 0.54, 0.12, and 0.06 g L⁻¹ day⁻¹ respectively. Irrespective of the type of photobioreactor, the productivities were P. carterae > E. huxleyi > G. oceanica. Pleurochrysis carterae lipid (20–25% of dry weight) and calcium carbonate (11–12% of dry weight) contents were also the highest of all species tested. Biotechnol. Bioeng. 2011;108:2078–2087. © 2011 Wiley Periodicals, Inc.     

Pyrogenic carbon capture and storage

The growth of biomass is considered the most efficient method currently available to extract carbon dioxide from the atmosphere. However, biomass carbon is easily degraded by microorganisms releasing it in the form of greenhouse gases back to the atmosphere. If biomass is pyrolyzed, the organic carbon is converted into solid (biochar), liquid (bio‐oil), and gaseous (permanent pyrogas) carbonaceous products. During the last decade, biochar has been discussed as a promising option to improve soil fertility and sequester carbon, although the carbon efficiency of the thermal conversion of biomass into biochar is in the range of 30%–50% only. So far, the liquid and gaseous pyrolysis products were mainly considered for combustion, though they can equally be processed into recalcitrant forms suitable for carbon sequestration. In this review, we show that pyrolytic carbon capture and storage (PyCCS) can aspire for carbon sequestration efficiencies of >70%, which is shown to be an important threshold to allow PyCCS to become a relevant negative emission technology. Prolonged residence times of pyrogenic carbon can be generated (a) within the terrestrial biosphere including the agricultural use of biochar; (b) within advanced bio‐based materials as long as they are not oxidized (biochar, bio‐oil); and (c) within suitable geological deposits (bio‐oil and CO₂ from permanent pyrogas oxidation). While pathway (c) would need major carbon taxes or similar governmental incentives to become a realistic option, pathways (a) and (b) create added economic value and could at least partly be implemented without other financial incentives. Pyrolysis technology is already well established, biochar sequestration and bio‐oil sequestration in soils, respectively biomaterials, do not present ecological hazards, and global scale‐up appears feasible within a time frame of 10–30 years. Thus, PyCCS could evolve into a decisive tool for global carbon governance, serving climate change mitigation and the sustainable development goals simultaneously.     

Sepharose-bound, highly sulfated glycosaminoglycans can capture HIV-1 from culture medium

In the search for new strategies against HIV-1 and on the basis of a number of previous studies reporting on the capacity of certain polyanionic compounds to influence the replication of HIV-1, we prepared a few chemically oversulfated dermatan and chondroitin sulfates. Four of these compounds and two samples of heparin were bound to activated Sepharose through either their carboxylic groups, or their aldehydic groups, or their deacetylated primary amino groups. Some of these so-derivatised resins, packed into columns, proved able to remove HIV-1 IIIB, a laboratory adapted strain, and one clinical primary isolate from an AIDS patient, from infected cell culture medium. The resins bind the virus very tightly and could be useful for capturing the virus from infected fluids.     

Diffusion chamber studies of carbon flux from living algae to heterotrophic bacteria

The flux of recently photosynthetically fixed, dissolved organic carbon (PDOC) from phototrophs to heterotrophic microorganisms was measured directly in microplankton samples from Lake Kinneret using a diffusion chamber technique. The minimum amounts of PDOC incorporated into small <3 µm heterotrophs during a 12 h light period ranged from 0.8 to 38.4 µg (C) l^-1, or from 0.2% to 6% of net primary productivity. Although quantitatively small in comparison with total photosynthetic fixation, this PDOC flux could yield about 2 to 3 × 10⁶ bacterial cells.ml^-1 daily. This experimental is consistent with previous estimates of algal PDOC release in this lake.     

COMBO: a defined freshwater culture medium for algae and zooplankton

In order to conduct experiments on interactions between animals and food organisms, it is necessary to develop a medium that adequately supports the growth of both algae and zooplankton without the need to alter the medium to accommodate either the algae or the animals. We devised a freshwater medium, named COMBO, that supports excellent growth of both algae and zooplankton. Two types of algae, Ankistrodesmus falcatus and Stephanodiscus hantzschii, were reared in COMBO and their growth rates were not significantly different from those of algae grown in a reference medium (WC). One of these algae, A. falcatus, was then fed to a cladoceran, Daphnia pulicaria, which was also cultured in COMBO, and the resulting fecundities of D. pulicaria were compared to those of animals reared in natural surface water. We also determined whether the value of COMBO as a medium for D. pulicaria was affected by modifications in nitrogen or phosphorus concentration to evaluate whether the new medium will be useful in nutritional research. Lowering the N or P content of COMBO did not affect the reproductive performance of D. pulicaria. Other researchers have also reported excellent growth and reproduction by numerous algae and zooplankton reared in COMBO. Our results suggest that COMBO is an effective artificial, defined culture medium capable of supporting robust growth and reproduction of both freshwater algae and zooplankton. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inorganic carbon acquisition in some synurophyte algae

Some characteristics of photosynthesis of three synurophyte algae, Synura petersenii, Synura uvella and Tessellaria volvocina were investigated to determine the mechanism of inorganic carbon (C(i)) uptake. All three species were found to have no external carbonic anhydrase, no capacity for direct bicarbonate uptake and a low whole-cell affinity for C(i). The internal pH of S. petersenii determined using (14)C-benzoic acid and [2-(14)C]-5,5-dimethyloxazolidine-2,4-dione was pH 7.0-7.5, over an external pH range of 5.0-7.5. Thus, the pH difference between the cell interior of S. petersenii and the external medium was large enough, over the alga's growth range, to allow the accumulation of C(i) by the diffusive uptake of CO(2). Monitoring O(2) evolution and CO(2) uptake by suspensions of S. petersenii at pH 7.0 by mass spectrometry did not indicate a rapid uptake of CO(2), and the final CO(2) compensation concentration reached was 24 +/- 0.7 microM. Furthermore, when the cells were darkened, a brief burst of CO(2) occurred before a steady rate of dark respiration was established, suggesting a loss of CO(2) by photorespiration. An examination of the kinetics of ribulose-1,5-bisphosphate carboxylase/oxygenase in homogenates of cells of S. petersenii, S. uvella and Mallomonas papillosa showed that values of the K(m) (CO(2)) were 28.4, 41.8 and 18.2 microM, respectively. These species lack the characteristics of cells with a CO(2)-concentrating mechanism because the cell affinity for C(i) appears to be determined by the relatively high CO(2) affinity of the Rubisco of these algae.     

Biotechnology for the acceleration of carbon dioxide capture and sequestration

The potential for enzymatic acceleration of carbon dioxide capture from combustion products of fossil fuels has been demonstrated. Carbonic anhydrase (CA) accelerates post combustion CO(2) capture, but available CAs are woefully inadequate for the harsh conditions employed in most of these processes. In this review, we summarize recent approaches to improve CA, and processes employing this enzyme, to maximize the benefit from this extremely fast biocatalyst. Approaches to overcoming limitations include sourcing CAs from thermophilic organisms, using protein engineering to evolve thermo-tolerant enzymes, immobilizing the enzyme for stabilization and confinement to cooler regions and process modifications that minimize the (thermo-, solvent) stress on the enzyme.     

Growth inhibitors produced by the green algae (Volvocaceae)

Summary A complex system of growth inhibition is present in the green algae (Volvocaceae). Inhibitors are found in the culture filtrates of some genera which limit their own growth (autoinhibition) while others in the family produce inhibitors which check the growth of other genera (heteroinhibition). These inhibitors are destroyed by autoclaving.     

Influence of algae species,substrata and culture conditions on attached microalgal culture

The objective of this study was to understand and optimize the formation of microalgae biofilms in specific culture conditions. Firstly, the adhesion of six freshwater algae species was compared. Chlorococcum sp. was selected because of the high adhesion biomass productivity (ABP) and adhesion rate achieved. Secondly, the adhesion of Chlorococcum sp. was compared with nine commonly used supporting materials, and glass fiber-reinforced plastic proved to be the optimal substrata. Thirdly, based on response surface methodology experiments, a second-order polynomial model was developed to examine the effect of culture period, initial total nitrogen concentration (ITNC) in manure wastewater, pH and culture volume of the growth chamber on the adhesion of Chlorococcum sp. using glass fiber-reinforced plastic. The experimental and modeling results showed that ITNC, pH and culture volume as well as the interactions between culture period and ITNC, culture period and culture volume were significant on ABP. Optimum culture conditions were predicted at a culture period of 11 days, ITNC of 70 mg L^?1, pH of 8 and culture volume of 340 mL, under which the predicted maximum ABP was 4.26 g m^?2 day^?1. The prediction was close to validation experimental results, indicating that the model could be used to guide and optimize the attached culture of Chlorococcum sp. using glass fiber-reinforced plastic.     

Isolation and culture of pluripotent cells from in vitro produced porcine embryos

The present study was designed to examine whether in vitro produced porcine embryos can be used to establish an embryonic stem (ES) cell line. Porcine embryos were produced by in vitro maturation and in vitro fertilization. Embryos at the 4-cell to blastocyst stages were cultured in an ES medium containing 16% fetal bovine serum with mouse embryonic fibroblasts as a feeder layer. It was found that ES-like colonies were derived only from blastocysts. When these ES-like colonies were separated in 0.25% trypsin-0.02% EDTA solution and cultured again, ES-like colonies were further observed in the subsequent culture until the fourth passage. The cells from ES-like colonies showed positive alkaline phosphatase activity. Some cells from the colonies differentiated into several types of cells in vitro when they were cultured in the medium without feeder layers and leukemin inhibitory factor. Embryoid bodies were also formed when the cells were cultured in a suspension status. These results indicate that porcine ES-like cells can be derived from in vitro produced porcine blastocysts and these ES-like cells are pluripotent. The culture system used in the present study is useful to isolate and culture ES cells from in vitro produced porcine embryos.     

Bicarbonate effects in leaf discs from spinach

In this paper, we show the unique role of bicarbonate ion in stimulating the electron transfer of photosystem II (PS II) in formate-treated leaf discs from spinach. This is referred to as the bicarbonate effect and is independent of the role of CO₂ in CO₂ fixation. It is shown to have two sites of action:

Mercury removal by immobilized algae in batch culture systems

The accumulation and volatilization of mercury by non-immobilized and immobilizedChlorella emersonii have been studied in batch culture systems. Reduction in the mercury concentration in the growth medium by non-immobilized cells was highly dependent on inoculum density, whilst reduction in mercury concentration by immobilized cells was rapid at all inoculum densities. Mercury accumulation by immobilized cell biomass was significantly greater than by non-immobilized cells with 10⁶ and 10⁵ cells bead^–1 or ml^–1. Volatilization of mercury by non-immobilized cell systems was greatest at higher inoculum densities, whereas more mercury was volatilized from immobilized cell systems at lower inoculum densities, and was greatest with unstocked alginate beads. Thus, in immobilized systems, mercury removal from solution is complex and involves mercury accumulation by the cells and volatilization by the matrix and cells. Further studies of mercury accumulation and volatilization by unstocked immobilization matrices revealed that agarose volatilized much less mercury than alginate or agar. The precise mechanism of mercury volatilization by alginate remains unclear, though it is thought to be a chemical effect.     

Pharmaceuticals from cultured algae

Summary An algae screening program, including cultured macroalgae, cultured cyanobacteria and cultured eukaryotic microalgae has been undertaken. Methods for the isolation, purification, preservation and cultivation of axenic cyanobacteria and eukaryotic cultures have been developed. Screening of these groups for biologically active components has lead to the isolation of pachydictyol and caulerpenyne from cultured macroalgae, while a series of hapalindoles and an antifungal depsipeptide have been isolated from cyanobacteria.     

Environmental assessment of German electricity generation from coal-fired power plants with amine-based carbon capture

Background, aim, and scope  

One of the most important sources of global carbon dioxide emissions is the combustion of fossil fuels for power generation. Power plants contribute more than 40% of the worldwide anthropogenic CO₂ emissions. Therefore, the increased requirements for climate protection are a great challenge for the power producers. In this context a significant increase in power plant efficiency will contribute to reduce specific CO₂ emissions. Additionally, CO₂ capture and storage (CCS) is receiving considerable attention as a greenhouse gas (GHG) mitigation option. CCS allows continued use of fossil fuels with no or little CO₂ emissions given to the atmosphere. This could approve a moderate transition to a low-carbon energy generation over the next decades. Currently, R&D activities in the field of CCS are mainly concentrated on the development of capture techniques, the geological assessment of CO₂ storage reservoirs, and on economic aspects. Although first studies on material and energy flows caused by CCS are available, a broader environmental analysis is necessary to show the overall environmental impacts of CCS. The objectives in this paper are coal-based power plants with and without CO₂ capture via mono-ethanolamine (MEA) and the comparison of their environmental effects based on life cycle assessment methodology (LCA).     

Dual functional nisin-multi-walled carbon nanotubes coated filters for bacterial capture and inactivation

Background

Removal of pathogens from water is one way to prevent waterborne illness. In this paper, we developed dual functional carbon nanotube (CNT) modified filters for bacterial capture and inactivation, utilizing multi-walled CNTs (MWCNTs) to coat on commercially available filters and making use of the exceptional adsorption property of CNTs to adsorb a natural antimicrobial peptide-nisin on it. Two types of MWCNTs with different outer layer diameters were used (MWCNTs1: <8 nm in diameter; MWCNTs2: 10–20 nm in diameter).

Results

The thickness of MWCNT layers, surface morphology, and surface hydrophobicity of both types of MWCNT coated filters were characterized. The MWCNT coating on filters significantly increased the surface hydrophobicity. The absorption of nisin and the capture of bacterial pathogens were correlated with increased surface hydrophobicity. The MWCNTs1 and MWCNTs2 filters with 1.5 mg MWCNTs loading captured 2.44 and 3.88 log of cells, respectively, from aqueous solutions containing a total of ~10⁶ CFU/mL cells. Nisin deposit at the amount of 0.5 mg on the surfaces of MWCNT filters significantly reduced the viability of captured B. anthracis cells by 95.71–97.19 %, and inhibited the metabolic activities of the captured cells by approximately 98.3 %.

Conclusions

The results demonstrated that the MWCNT-nisin filters achieved dual functions in bacterial pathogen capture and inhibition in one single filtration step, which is potentially applicable in removing undesired microorganisms from water sources and inhibiting captured Gram positive bacteria activities.

     

Ultrahigh bioproductivity from algae

The potential for dramatic increases in bioproductivity in algal photobioreactors relative to current biomass approaches, e.g., for converting sunlight into biofuels, by an unorthodox integration of photonics and biotechnologies is described. The key to greater biomass yields—projected as high as 100 g dry weight m⁻² h⁻¹—is a pronounced heightening of algal flux tolerance, achieved by tailoring the photonic temporal, spectral and intensity characteristics with pulsed light-emitting diodes. Such tailored photonic input is applied in concert with thin-channel ultradense culture photobioreactors with flow patterns that produce rapid light/dark algae exposure cycles. The artificial-light scheme is globally feasible only with electricity generated from renewables. Recent advances in ultra-efficient concentrator photovoltaics, as well as high-performance light-emitting diodes, create a practical reality for converting sunlight into pulsed red light and delivering it to indoor photobioreactors, with characteristic pulse times and intensities optimally suited to the rate-limiting dark reactions of photosynthesis. Cellular engineering built upon recent progress in modifying algal chlorophyll antenna size, in combination with metabolic engineering, could further enhance bioproductivity. The proposed strategy requires no major advances for implementation and adopts existing technologies. Revision submitted to Applied Microbiology and Biotechnology on 25 June 2007.